Long axons within the striate cortex: their distribution, orientation, and patterns of connection.

Abstract

Rockland and Lund (1982) observed that an injection of horseradish peroxidsae into the striate cortex of the tree shrew produces a patchy distribution of label adjacent to the injection site. They proposed that this pattern might be due to populations of neurons with long-range cortico-cortical connections that are interspersed with populations having no such connections. An alternative explanation accounts for the pattern by supposing that the label is carried by a system of oriented axons. These axons link may cells with similar orientation preferences and make their connections within a narrow strip of cortex whose direction is related to the orientation of the cells in question. Such connections could be involved in generating complex receptive fields from simple ones. They may also be used to generate very elongated receptive fields, inhibitory flanks or end-stoping. Several experimental tests of these ideas are discussed [using tree shrew and cat models].